Here is the situation: Soybean cyst nematode (SCN) is the worst pest of soybeans in the U. S. A. including Missouri.
Fortunately, this pest can be managed, but farmers must take steps before planting soybean this year to protect their crop against these nematodes.
The first step is to test the soil for SCN, and this must be done in the next few days. This step must soon be completed so the test results will be available by early- to mid-April, and the information can be used to select varieties for planting this year. University of Missouri Extension Regional Agronomists have information about taking and submitting soil samples for SCN analysis, and more information is available at the University of Missouri web site http://soilplantlab.missouri.edu/nematode.
The second step is to make decisions about crops to plant in 2012. Farmers should plant corn or another crop resistant to SCN in fields that have a high population of SCN. Crop rotation is a great SCN control method because SCN numbers decline during years when crops such as corn, grain sorghum, a forage crop, or cotton are planted. The number of years these crops should be planted before planting soybean again will depend on the number of SCN in the soil. Soybean may be planted in fields that have a low population of SCN in the soil, but farmers should only plant varieties with some type resistance to SCN.
Soybean cyst nematode resistant varieties are available and most yield well. Very few varieties are resistant to all types of SCN so selecting the best variety to plant is difficult. Information about soybean variety resistance to SCN is available at University of Missouri Extension Offices. The University of Missouri Variety Testing web site shows information that was provided by seed companies, http://varietytesting.missouri.edu/soybean/soybean_characteristics_2011.pdf. Visitors to this site should select "Soybean", and then select "Characteristics". Farmers should also ask the representatives for the soybean seed companies they buy from about the best SCN resistant varieties to plant in each field. These are the only useful SCN control methods available.
More information about SCN management is available in the University of Missouri Extension Guide titled, Soybean Cyst Nematode: Diagnosis and Management. This guide is available at http://muextension.missouri.edu/xplor/agguides/crops/g04450.htm.
The Missouri soybean farmer checkoff managed by the Missouri Soybean Merchandising Council funded much of the research by University of Missouri scientists to develop SCN resistant varieties and determine that crop rotation is a great SCN management tool.
Following these suggested procedures will give soybean farmers a better chance of producing a profitable soybean crop in 2012.
REVISED: September 30, 2013